Journal 0fNatwal P&s Vol. 53, No. 2, pp. 496-497, *-A@ 1990
496
PIPEROLACTAM D, A NEW ARISTOLACTAM FROM INDIAN PZPER SPECIES SANjAY J.
DESAI,ROHITCHATURVEDI,
AND NEWAND B.
MULCHANDANI+
Bio-Organic Division, Bhabha Atomic Rcreurch Centre, T m b a y , Bombay 400 081,India ABSTRACT.-A new alkaloid was isolated from the cold EtOH extracts of Pipcrattewatnm and Piper boebmm$lium and has been characterized as lO-mino-2-hydroxy-3,4dimethoxyphenanthrene- 1-carboxylic acid lactam i l l .
Aristolactams, a small group of compounds found mainly in the Aristolochiaceae, have also been reported from some members of the Annonaceae, Menispermaceae, and Monimimaceae (1). Recently, we reported the isolation of aristolactams from Indian Piper species (2,3). In continuation of this work, we report the presence of a new aristolactam, named piperolactam D 111, from Piper uttenuutum (Cas.) DC. and P i p boehmerifoum Wall (Piperaceae). Piperolactam D [l],obtained as a yellow crystalline solid, gave a molecular ion peak at eims m/z 295 (100%) suggesting Cl7Hl3NO4.It exhibited uv absorption peaks characteristic of a phenanthrene chromophore. An alkaliinduced bathochromic shift suggested the presence of a phenolic group. The presence of a hydroxyl band (3390 cm- ') was confirmed in the ir spectrum. Appearance of ir bands at 3180 (NH), 1690, and 1650 cm-' (C=O) suggested the presence of a lactam. Acetylation of 1 yielded a diacetate, C2,Hl7N06, [MI+ 379, which further supported the
presence of -OH and -NH groups. Methylation of 1 with CH2N2furnished a compound identical with piperolactam C E21 (co-tlc, ms) (3) suggesting that 1 is a phenolic analogue of 2. The 500 MHz 1 H-nmr spectrum of 1 showed two methoxy signals at 6 3.85 and 4.40, each integrating for three protons. The absence of a C-2 proton signal in 1, when compared with 3-5 (2), indicated a 2,3,4 trisubstituted pattern. The aromatic region of the spectrum closely resembled those of aristolactams unsubstituted at positions 5-9 (4). Therefore, the two methoxy groups were determined to be in ring A. The methoxy signals in 1 (6 3.85 and 4.4) were at variance with the other two possible isomeric structures 6 E6 3.98 and 4.03 (2)1 and 7 [6 4.17 and 4.62 (4), 6 4.16 and 4.61 (5)1. Therefore, the two methoxy groups were assigned to the C3 and C-4 positions. In addition, the upfield methoxy signal (6 3.85), due to the shielding effect of the C-2 hydroxyl, was assigned to C-3. Thus, structure 1 was established as lO-amino-2-hydroxy-3,4dimethoxyphenanthrene-1-carboxylic acid lactam. EXPERIMENTAL
1
R,=R,=OMe, R,=OH, R4=H
2 R,=R,=R,=OMe, R4=H
3 R,=R,=OMe, R,=R4=H 4
R , =OMe, R2=OH, R3=R4=H
5 R,=OH, R2=OMe, R,=R4=H 6 R,=OH, R,=R,=OMe, R4=H 7 R,=R,=OMe, R,=OH, R4=H
GENERAL EXPERIMENTAL PROCEDURESMp's were determined on a Fisher-Johns apparatus and are uncorrected. The uv spectra were obrained in MeOH on a Shimadzu uv-visible 240 spectrophotometer. The ir spectra were taken from KBr pellets on a Perkin-Elmer 783 ir spectrophotometer. The 'H-nmt spectrum was recorded in DMSO-& (6 in ppm), using TMS as internal standard on a Bruker Spectrospin 5 0 0 MHz spectrometer. Eims were recorded on Shimadzu gdms-QP lOOOA at 70 eV. Elemental analyses
Mar-Apr 19907
Desai et al. : Aristolactam from Pipw
were carried out on a Carlo Erba Model 1106 Elemental Analyzer. Si gel (23@-400 mesh size, Acme India) was used for vacuum liquid chromatography. Fractions from cc in each case were separately combined on the basis of their tlc patterns as detected by uv light (254 and 365 nm). PLANT COLLECTION, EXTRACTION, AND
ISOLATION.-The whole dried plant material (2 kg each) of P. atrenuaturnand P. bwhmererifolirrmwas obtained from M / s United Chemicals and Allied Products, Glcutta, with whom the voucher specimens are available. The plant materials were extracted successively with petroleum ether and ErOH by percolation. The extracts were concentrated under reduced pressure. Subsequent column and tlc separation over Si gel [CHCI,MeOH(19:1), Rf0.55]afforded 1(P. attmutwn, 6 mg; P. h h m e r ~ o l i u m7, mg) in pure form. PIPEROLACTAMD [I].-Yellow crystalline solid, mp 226227" (C6HdMeOH); uv max nm (log e) (MeOH) 225 (4.68), 269 (4.92), 293 (4.5% 337(4.35), 373(4.10);uv~maxnm(log e)(MeOH+KOH)235 (4.83), 266(4.51), 294 (4.81), 329 (4.27), 362 (4.33), 381 (4.30); ir v max (KBr) cm-I 3390, 3180, 1690, 1650, 1405, 1260; eims d z (%) [MI+ 295 (loo), 280 (55). 252 (28.2), 277 (13.4), 276 (12. l), 266 (14. I), 234 (13.6), 209 (20.5), 153 (191, 152 (12), 149 (16.4), 166 (16.9). 119 (19); 'H nmr (DMSO-& 6 3.85 (3H, s, OMe), 4.40 (3H, s, OMe), 7.24 (IH, s, H-9), 7.53 (2H, m, H-6 and H-7), 7.95 (IH, m, H-8), 9.26 ( l H , m, H-5), 10.8 ( I H , s, NH). Anal. calcd for C,7H,3N04, C 69.15, H 4.41, N 4.75; found C 69.17, H 4.36,N4.68%.
497
ACETYLATION OF 1.-Pure 1(3 mg) was dissolved in pyridine (0.5 ml) and treated with Ac20 (0.5 ml). The reaction mixture was allowed to stand at room temperature overnight and after usual workup yielded a viscous mass purified by tlc over Si gel: yellow crystalline solid, mp 192193" (petroleum ether/C,Hd; ir Y max cm-' (KBr) 1790, 1740, 1720, 1640, 1480, 1400, 1380, 1310, 1280, 1190, 1160, 1150, 1090, 1080, 1020; eims m/z (%) [MI+ 379 (45.7), 358 (5.6), 337 (89), 295 ( 9 6 , 280 (67), 277 (22), 266 (17), 252 (21), 236 (21.6), 209 (17. I), 180 (13.6), 152 (13.6), 105 (39). Anal. calcd for C2,HI7NO6,C 66.49, H 4.49, N. 3.69; found C 66.46, H 4.43, N 3.64%. ACKNOWLEDGMENTS SJD and RC are grateful to the DAE for the award of Senior Research Fellowships. Thanks are also due to the operator of the 500 MHz FT-nmr National Facility, TIFR, Bombay, for recording the spectra. LITERATURE CITED 1. D.B. Mix, H. Guinaudeau, and M. Shamma,J . Nut. Prod., 45,657 (1982). 2. S.J. Dew, B.R. Prabhu, and N.B. Mul27, 15 l l (1988). chandani, Phytorhemi~t~, 3. S.J. Desai, R. Chaturvedi, L.P. Badheka, and N.B. Mulchandani, Indian J . Chem., 28B,775 (1989). 4. S.K. Talapatra, D. Basu, P. Chattopadhyay, and B. Talapatra, P h y t ~ h i ~27, t ~ 903 , (1988). 5 . N. Sun, M. Antoun, C. Chang, and J.M. Cassady,J . Nut. Prod., 50,843 (1987). R u e i d 10July 1989
